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30 lines
1.4 KiB
C
30 lines
1.4 KiB
C
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#ifndef COSMOPOLITAN_LIBC_INTRIN_CMPXCHG_H_
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#define COSMOPOLITAN_LIBC_INTRIN_CMPXCHG_H_
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#include "libc/bits/asmflag.h"
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#if !(__ASSEMBLER__ + __LINKER__ + 0)
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COSMOPOLITAN_C_START_
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bool _cmpxchg(void *, intptr_t, intptr_t, size_t);
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#if defined(__GNUC__) && !defined(__STRICT_ANSI__) && defined(__x86__)
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#define _cmpxchg(IFTHING, ISEQUALTOME, REPLACEITWITHME) \
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({ \
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bool DidIt; \
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autotype(IFTHING) IfThing = (IFTHING); \
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typeof(*IfThing) IsEqualToMe = (ISEQUALTOME); \
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typeof(*IfThing) ReplaceItWithMe = (REPLACEITWITHME); \
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asm volatile(ZFLAG_ASM("cmpxchg\t%3,%1") \
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: ZFLAG_CONSTRAINT(DidIt), "+m"(*IfThing), "+a"(IsEqualToMe) \
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: "r"(ReplaceItWithMe) \
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: "cc"); \
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DidIt; \
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})
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#else
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#define _cmpxchg(MEM, CMP, VAL) \
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_cmpxchg(MEM, (intptr_t)(CMP), (intptr_t)(VAL), sizeof(*(MEM)))
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#endif /* GNUC && !ANSI && x86 */
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COSMOPOLITAN_C_END_
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#endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */
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#endif /* COSMOPOLITAN_LIBC_INTRIN_CMPXCHG_H_ */
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